Discrepancy in dengue virus neutralizing antibody titers between plaque reduction neutralizing tests with Fcgamma receptor (FcgammaR)-negative and FcgammaR-expressing BHK-21 cells.

Protective immunity against dengue virus (DENV) is best reflected by the presence of neutralizing antibodies. The conventional plaque reduction neutralizing test (PRNT) is performed using Fcgamma receptor (FcgammaR)-negative cells. Because FcgammaR plays a key role in antibody-dependent enhancement, we examined neutralizing antibody titers of mouse monoclonal antibodies and human serum samples in PRNTs using FcgammaRIIA-negative and FcgammaRIIA-expressing BHK cells. There was a discrepancy in dengue virus neutralizing antibody titers between PRNTs using FcgammaRIIA-negative versus FcgammaRIIA-expressing BHK cells. Neutralizing antibody titers to DENV-1 and DENV-2 tested with monoclonal antibodies, and with most of the human serum samples, were higher in assays using BHK cells than those using FcgammaRIIA-expressing BHK cells. The results suggest that neutralizing antibody titers determined using FcgammaRIIA-expressing cells may better reflect the protective capacity of anti-DENV antibodies, as the major target cells of DENV infection are FcgammaR-positive cells.